Common dates tasks
Measure elapsed calendar time between two dates.
Open calculator Age CalculatorCalculate completed age from a birth date and reference date.
Open calculator Day CounterCount selected weekdays with explicit calendar endpoints.
Open calculator Days From Today CalculatorFind the date a number of days, weeks or months away.
Open calculatorHow to use these calculators
Date and time questions depend on conventions as much as arithmetic. A date difference may exclude the starting day, a deadline may include both endpoints, and a work schedule may remove weekends or breaks. Choose the convention that matches the policy, contract or question before relying on the count.
Clock calculations need an actual date when daylight-saving transitions are possible. A fixed UTC offset is not the same thing as a named time zone because regional rules can change during the year. For payroll, travel or legal deadlines, compare the calculated value with the governing schedule and preserve the original timestamps.
Three checks that change the answer
Decide whether endpoints count
Inclusive counting adds the starting and ending dates; elapsed-time counting usually measures the interval between them.
Use a zone, not only an offset
Named zones can apply daylight-saving rules that a fixed UTC offset cannot represent.
Separate calendar and business days
Weekends and holidays must be handled explicitly when a rule calls for working days.
Before you use the answer
- Record the local time zone for each timestamp.
- Choose inclusive or exclusive endpoint counting.
- Add holidays separately when they matter.
- Verify overnight shifts and unpaid breaks.
Browse all 11 dates calculators
Every tool calculates in your browser. Pages marked “Reviewed guide” also include topic-specific explanations and source checks.
- Date CalculatorReviewed guideCount calendar days between two dates, including leap years.
- Age CalculatorReviewed guideFind exact age in years, months and days, with totals in weeks and days and a countdown to the next birthday.
- Day CounterReviewed guideCount calendar days, weekdays and weekends between two dates with explicit inclusion rules.
- Hours CalculatorReviewed guideCalculate a work shift, including an unpaid break.
- Time Duration CalculatorReviewed guideConvert hours, minutes and seconds into one duration.
- Time Card CalculatorReviewed guideAdd multiple shifts, unpaid breaks, weekly overtime and estimated gross pay.
- Time CalculatorReviewed guideAdd or subtract two durations in days, hours, minutes and seconds, with normalized totals and a transparent unit breakdown.
- Time Zone CalculatorReviewed guideConvert a local date and time between fixed UTC offsets, including half-hour and quarter-hour offsets.
- Day of the Week CalculatorReviewed guideFind the weekday for a Gregorian calendar date without a time-zone shift.
- Days From Today CalculatorReviewed guideFind the date that falls a number of days, weeks, months or years after or before today or any start date, with calendar or business days.
- Military Time ConverterReviewed guideConvert standard 12-hour time with AM and PM to military (24-hour) time and back, with the spoken form.
Frequently asked questions
Why is a date difference one day shorter than my count?
You may be counting both calendar dates while the calculator is measuring elapsed time between their boundaries.
Is a year always 365 days?
No. Leap years have 366 days, so exact date arithmetic should use calendar dates.
Can a fixed offset handle daylight saving time?
No. A named time zone and date are needed to apply regional clock changes.
Are business-day results legal deadlines?
They are planning calculations. Court, banking and agency calendars can define holidays and cutoff times differently.
Reference starting points
Individual reviewed guides cite the equation or standard used by that calculator. These authorities provide broader context for this collection.